The scandal involving an affair between former CIA Director David Petraeus and military expert Paula Broadwell could expand much further than originally thought.

In a new twist, the Pentagon is investigating Gen. John Allen, a top U.S. commander in Afghanistan, for allegedly sending "inappropriate emails" to Jill Kelley. Kelley is the woman who prompted the investigation of Petraeus after alerting the FBI she was receiving threatening emails from Broadwell.

Although Allen has denied any wrongdoing, U.S. officials say there are 20,000 to 30,000 emails between Allen and Kelley.

Is there any possible White House cover up in all this? CBN News Congressional Correspondent John Jessup has more from Capitol Hill, following this report.

Meanwhile, new details of Petraeus' affair continue to emerge. Agents spent hours at Broadwell's home Monday night, leaving with files, boxes, and a computer.

Petraeus denies giving Broadwell any of the sensitive military information allegedly found on her computer.

Authorities say extramarital affairs are particularly risky for intelligence officers because it could be used as blackmail.

"In his universe, this moral failing is unacceptable and renders him unworthy of continuing this position of responsibility of the nation," retired Army Lt. Col. John Nagl said.

More questions are also being raised Tuesday about why the FBI waited until after the election to alert the White House about the Petraeus affair.

Lawmakers say the FBI was not just conducting a criminal investigation of an alleged email harassment case. The agency was also looking into whether a separate set of emails between Petraeus and Broadwell might involve a security breach.

"It just doesn't add up that the FBI would be carrying on this type of investigation without...bringing it to the president or the highest levels of the White House," Rep. Peter King, R-N.Y, chairman of the Homeland Security Committee, said.

The FBI is expected to present a timeline of its investigation to Congress at a meeting on Wednesday.

Efrem Graham

News Anchor & Reporter

Efrem Graham is an award-winning journalist, who comes to CBN News from the ABC owned and operated station in Toledo, Ohio. He received his master's degree from the Columbia University Journalism School. He also holds a bachelor's degree in English Literature from the Richard Stockton College of New Jersey. Follow Efrem on Twitter @EfremGraham and "like" him at Facebook.com/EfremGrahamCBN.